COMEDK2022PhysicsMagnetic Effects of Current
A circular coil of 20 turns and radius 10 cm is placed in a uniform magnetic field of 0.10 T normal to the plane of the coil. If the current in the coil is 5 A, the cross-sectional area of the wire is 10⁻⁵ m ^2 , and the free electron density is 10²⁹ m ⁻³ , then the average force on each electron in the coil due to the magnetic field is:
Options
- A2.5 10⁻²⁵ ~N
- B4.5 10⁻²⁵ ~N
- C5 10⁻²⁵ ~N
- D5.5 10⁻²⁵ ~N
Correct answer
C. 5 10⁻²⁵ ~N
Step-by-step solution
Force on one electron: F = ev_d B From I = nAev_d ev_d = I nA F = IB nA = 5 0.10 10²⁹ 10⁻⁵ = 0.5 10²⁴ = 5 10⁻²⁵ , N (Number of turns and radius do not affect the force on an individual electron.) Correct option: (3)